The global minimum tax is no longer a theory. On 6 January 2026, the Luxembourg tax authorities opened the Pillar Two registration and filing forms on MyGuichet, and the first deadline is now in sight: 30 June 2026 for groups with a calendar 2024 financial year. Here is what needs to be done, and why your Luxembourg holding company may be concerned even if it does not consider itself part of a “multinational”.
Who is in scope
The Luxembourg law of 22 December 2023 implements the EU Minimum Tax Directive, itself based on the OECD Pillar Two rules. It applies to multinational groups and large domestic groups whose consolidated revenue reached at least EUR 750 million in at least two of the four preceding financial years. Any Luxembourg entity that is fully consolidated in the accounts of such a group is in principle a constituent entity, unless a specific exclusion applies.
This is where many private equity, real estate and family office structures should pay attention. Being “just a holding company” does not take you out of scope: what matters is whether the Luxembourg entity belongs to a group that crosses the EUR 750 million threshold. Exclusions exist, notably for investment funds and real estate investment vehicles at the top of a group and for some of the entities they own, but they must be analysed rather than assumed.
What needs to be filed
Three obligations now apply to in-scope Luxembourg entities:
- a registration on MyGuichet for each constituent entity, which also serves to notify which group entity will file the GloBE Information Return (GIR);
- the GIR itself, which follows the OECD template and may be filed by a single group entity abroad, provided an agreement between tax authorities allows its automatic exchange with Luxembourg;
- a short local top-up tax return, with any tax due to be paid within one month of filing.
All obligations must be met within 18 months of the end of the first financial year in scope, hence 30 June 2026 for calendar 2024, and within 15 months for the following years, hence 31 March 2027 for calendar 2025.
The penalties are not symbolic: EUR 5,000 per entity for a missing registration, up to EUR 250,000 for an incomplete, late or incorrect GIR or top-up tax return, and up to EUR 300,000 where a GIR filed abroad is missing or cannot be evidenced.
The side-by-side package
On 5 January 2026, the OECD Inclusive Framework agreed on a “side-by-side” package. In short, groups headquartered in a jurisdiction with a qualifying minimum tax regime, which currently means the United States only, are switched off from the income inclusion rule and the undertaxed profits rule. Domestic minimum top-up taxes, including Luxembourg’s, continue to apply. The package must still be transposed into Luxembourg law, and it does not remove the 2024 filing obligations.
We are here to help
With less than five months to go, the first step is simple: confirm whether your Luxembourg entities are in scope, and who in the group files what. JW Partner can help you map your entities, coordinate with your group’s tax team and complete your Luxembourg registrations and returns. Feel free to reach out to us at contact@jwpartner.lu.